Deep brain stimulation (DBS) of the basal ganglia is an effective treatment for select movement disorders, including Parkinson’s disease, essential tremor and dystonia. Based on these successes, DBS has been explored as an experimental treatment for medication-resistant neuropsychiatric disease. During a multiyear experience employing DBS to treat patients for obsessive compulsive disorder (OCD) we encountered several unanticipated stimulation-induced psychiatric side effects. We present a case of a young woman treated for OCD with DBS of the anterior limb of the internal capsule and nucleus accumbens region, who subsequently manifested a manic episode. We aim to discuss the case details, treatment and potential neuroanatomical underpinnings of this response.